This application includes a microfiche appendix consisting of nine (9) microfiche and 491 frames.
This invention relates generally to apparatus for recording information from a master medium onto a slave medium, and, more particularly, to apparatus for transferring audio signals from a master medium, such as a source tape, at high speeds onto a slave medium such as the magnetic tape of an audio cassette.
Heretofore, duplicating equipment for the mass production of prerecorded magnetic tapes containing music or language programs employed a device for reproducing a master or like source and a device for recording the reproduced information on slave tapes. In one approach, a "running master" is installed on a playback device and during playback is advanced as an endless loop through a temporary storage bin. A slave tape in the form of a "pancake" of a length sufficient to replicate many times the programs stored on the endless loop tape is placed on each of several slave transports and moved at a speed which is a synchronous multiple of the recording speed of the original master. The master tape is advanced through the temporary storage bin a sufficient number of times to reproduce the program information on a desired number of segments of each slave tape, which usually is done at a speed which is multiple of the speed of which the information was recorded on the master tape, typically, sixty-four.
The "running master" duplication approach has many drawbacks including breakage both of master and slave tapes which require shutdown to correct, master tape wear which requires frequent replacement and thus the need for many copies of the master, and abrasion of the playback head by the movement of the master tape thereacross with resulting degradation in the frequency response of the system. The cost consequence of such failures is the time lost to stop the duplication process to replace the master tape, replace and/or recue the slave tape to the proper start point, and restart the duplication process.
Another early tape duplicating apparatus for transferring information from a master tape onto plural slave tapes employed a reel-to-reel master tape transport and on play-through the information was recorded on each of the slave tapes. Thereafter, the master had to be rewound and then replayed to transfer the master information to the slave tapes a second time, and so on, an obviously unacceptably slow process for the mass production of prerecorded programs.
A tape duplicating apparatus described in U.S. Pat. No. 4,410,917 to Newdoll et al, addresses the tape wear and breakage problem of such earlier systems and seeks to increase the duplicating speed. In this system, information recorded on master tape, which may be in either analog or digital form, is reproduced from the master medium at the same speed at which it is recorded, normally real time or a small multiple (e.g., two or four) of real time. The reproduced information is stored in a digital storage device (in the analog case after conversion to digital information) at the same rate at which it was reproduced. The digital information is then recovered from the digital store at a rate which is a multiple of the digital recording speed, is converted to analog information and applied to a recording device for recording on a slave medium. The rate at which the digital information is recovered from the digital storage device and applied to the slave tape is not specified, other than that it is faster; however, the described equipment suggests that the multiple was only about six times real time. Furthermore, the method of bit-rate reduction used to achieve this speed puts in doubt the audio quality of the duplicated product.
While Newdoll et al. substantially eliminated master tape wear, and wear and tear of the playback head of the master reproducing device, and achieved some increase in duplicating speed over the prior art systems, the system would be inefficient and impractical in a production environment. Assuming, for example, a typical line in which digital information from the digital store is converted to analog and applied in parallel to fifteen duplicating machines, when the pancakes on the duplicating machines are filled the operator stops them, removes the fully recorded pancakes and reloads the machines with new pancakes. Changing fifteen pancakes and cleaning and lacing up the machines takes about two minutes, not a major loss of time if the production schedule calls for additional replications of the program then stored in the digital store; however, should the schedule call for duplication of a different selection, the master tape, too, has to be changed, and however the program information is recorded, it has to be loaded, in real time, into the digital store. A typical one-hour program, that is, up to thirty minutes on each side of a cassette tape, would take one hour, resulting in a loss of at least fifteen machine-hours of production. This number becomes extremely significant in a major duplicating facility which typically may have seventy selection changes during an 8-hour production shift, of which there may be two and sometimes three per day.
Another tape duplicating system in which analog signals recorded on a master tape are converted to digital form, stored in a digital storage device, and then transferred to slave tapes after conversion to analog form, is described in U.S. Pat. No. 4,355,338. The digital store employs magnetic disks, each having plural magnetic head groups, on which digital signals are recorded on a time-axis compressed basis and driven in parallel to achieve increased signal transfer rate; the patent suggests that slave tapes can easily be obtained in 1/32nd of the normal tape translation speed. This system suffers the same disadvantage as the Newdoll et al. system, namely, that each time there is a selection change the slave machines are idled for the time required to load the new program information, typically an hour for a cassette tape recorded on both sides.
A primary object of the present invention is to provide apparatus for recording information reproduced from a master medium onto a slave tape medium which significantly improves the utilization of the slave tape machines.
Another object of the invention is to provide apparatus for recording information reproduced from a master medium which enables recording of information on the slave medium at the same time that information is being reproduced from the master medium.
It is another object of the invention to provide apparatus for duplicating information stored on a master medium in which master tape wear and tape breakage is essentially eliminated.
Still another object of the invention is to provide a method and apparatus for recording information reproduced from a master medium onto a slave tape medium at signal transfer rates which are large multiples of real time.
A further object of the invention is to provide a large duplicating system having many groups of duplicators each of which groups is capable of reproducing information from different sources and all or a desired number of which may reproduce information from a single source.